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Re: Assigning Credit to Players

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  • mikel_ind
    ... Any number from .1 to .9 might be appropriate. ... superior ... (If it s ... no great ... Passing to Bradley 30 feet away will yield no assists, so this
    Message 1 of 10 , Mar 14, 2002
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      --- In APBR_analysis@y..., "Michael K. Tamada" <tamada@o...> wrote:
      >
      > Here are my gut feel answers:
      > >
      > > 1. The point guard passes through the defense to a big man
      > > underneath ...., should they split credit 50-50?
      >
      > Passer 2/3, dunker 1/3.

      Any number from .1 to .9 might be appropriate.


      >...ideally we'd want the point guard to pass to unguarded good
      > shooters rather than unguarded mediocre shooters. It's a clearly
      superior
      > situation, and is likely to be harder for the passer to achieve.
      (If it's
      > Shawn Bradley 30 feet from the basket, getting the ball to him is
      no great
      > achievement).

      Passing to Bradley 30 feet away will yield no assists, so this credit
      is built-in.
      (Unless the clock is about to expire, and Bradley is the only guy
      open. In this case, not-passing-to-Bradley should get you yanked
      from the game.)

      > All that suggests that the passer should get more credit when
      passing to
      > the good shooter than the mediocre shooter.
      >.... So if Reggie Miller and Jeff Foster both hit open
      > 20 footers, should Reggie get less credit than Foster?
      >
      > Miller WILL make more of those baskets, so maybe it's okay to give
      him
      > less credit -- but it better not be TOO much less. Otherwise, he
      might go
      > 5-10 one night on open 20 footers, and Foster would go 4-10 ... and
      Foster
      > might be rated as having a better performance!

      Indeed, the longer you think about it, the more unimaginable the idea
      becomes. (Shouldn't Foster really be banging the boards, rather than
      hanging out at 20 feet?)

      > > 3. On a pick and roll, the guard gets double-teamed and finds the
      > > roll-guy near the basket for an open 5 ft shot.
      >
      > Guard gets 2/3 credit.
      >
      > >
      > > 4. On a pick and roll, the guard gets double-teamed and finds the
      > > roll-guy popping out for a 15 ft jump shot.
      >
      > Guard gets half credit.

      We could have concentric arcs that assign % credit in this way.
      While we're at it, install sensors under the floor, in the ball, and
      in the shoes of the players, so it is all tabulated electronically.

      This is reminiscent of some suggested extra arcs that give a team
      only 1 point inside 5 feet (or 10, or whatever), and 4 points beyond
      40 feet, etc.


      > > 5. On a pick and roll, the guard's man is picked off with no
      switch,
      > > freeing him for an open 18 ft jump shot.
      >
      > Guard gets 3/4 credit, pick-setter gets 1/4. Hmm, but how much of
      this
      > was not due to EITHER of them,

      Indeed, there are players setting picks for the pickers, acting as
      decoys, combining these actions with positioning for rebounding... My
      guess is, there are infinite possibilities you could consider.

      > but instead should be counted as a negative
      > against the defenders who failed to do their job? Should a made
      basket
      > always represent only positive things, to be apportioned among the
      > offensive players, or should we instead deduct some credits from the
      > defenders?

      Another odious can of worms: Negative statistics. Perhaps
      competition at any level should have some accounting system that adds
      up to zero. Every success is the result of some mistake.

      At a game, one is sometimes surrounded by fans who only see the
      negative aspects of the game, and a "positive" comment is "About time
      he hit that shot", or some such.

      I see the game as 90-99% beauty and excellence. Sometimes I can't
      remember the last time someone misplayed anything.

      If it were an orchestra, of course more than 90% of the notes have to
      be essentially perfect. But there is no D in music.

      What the heck were we talking about here?
    • alleyoop2
      Fascinating topic Dean. I put in my $0.02 below each item. ... Normally, I think the shooter should get most of the credit, since he has to both get open and
      Message 2 of 10 , Mar 14, 2002
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        Fascinating topic Dean. I put in my $0.02 below each item.

        --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
        >
        > I posed the following to a bunch of coaches. This group is a bit
        > tainted by my opinion, but I'll ask anyway...
        >
        > I am interested in obtaining some opinions on distributing
        > credit to players for different situations in basketball.
        >
        > For example
        >
        > 1. The point guard passes through the defense to a big man
        > underneath the basket for a dunk. What percentage of the credit for
        > the TEAM score should go to the passer vs. the scorer? Obviously,
        > one player gets an assist and one gets the field goal, but,
        > subjectively, should they split credit 50-50?

        Normally, I think the shooter should get most of the credit, since he
        has to both get open and make the shot. In this case, since the pass
        led directly to a dunk, I think it should be split more evenly. 50-
        50, or 60-40 for the shooter at worst.

        >
        > 2. A point guard passes to an unguarded mediocre shooter at the
        > perimeter who makes a jump shot. How should credit be split here?
        >

        Passing to a mediocre shooter is its own reward. He'll make a lower
        percentage so the guard will get fewer assist "credits." I would
        consider this a fairly normal assist and give 2/3 to the shooter, 1/3
        to the passer.

        > 3. On a pick and roll, the guard gets double-teamed and finds the
        > roll-guy near the basket for an open 5 ft shot.
        >
        > 4. On a pick and roll, the guard gets double-teamed and finds the
        > roll-guy popping out for a 15 ft jump shot.
        >

        Very little difference between these two IMHO, since a lot depends on
        where the roll guy decides to go. I'd go 2/3 for the shooter on each.

        > 5. On a pick and roll, the guard's man is picked off with no
        switch,
        > freeing him for an open 18 ft jump shot.
        >

        Interesting - a pick leading directly to a basket. Theoretically that
        should be worth as much as an assist. I would give as much as 1/3 of
        the credit to the screener.


        > 6. In situation 3, how do you split the credit/blame to the two
        > defenders who didn't shut down the pick and roll? Should the rest
        of
        > the team also receive blame? How much?
        >
        > 7. Same question for splitting defensive credit for #4.
        >
        > 8. Same question for splitting defensive credit for #5.
        >

        I think, if you're doing this, you have to assign -2 points to your
        defense somehow on this play. On the pick and roll it should probably
        be split among the two guys, unless one made a particularly poor play.

        > 9. A guard misses a jump shot, which is rebounded and stuck back in
        > by a teammate. How much credit goes to the two players?
        >

        Negative credit for the guard, unless you think he was passing it off
        the rim. Two credits for the rebounder - 1) regaining possession, and
        2) making the basket.

        > 10. A guard misses a jump shot, which is rebounded by a teammate.
        > He passes back to the guard to restart the offense, which, after
        > several passes, scores. How much credit should go to the offensive
        > rebounder?

        This is why I separate the regaining possession from making the
        basket above. Same negative credit to the guard.

        >
        > I'm not looking for formal studies, but rather gut feel from people
        > on these, maybe with some explanation for the answers, maybe
        > without. I recognize that coaches often don't think about
        > distributing credit this way and that it, in some ways, goes
        against
        > the spirit of the roles players should have. This is an attempt to
        > identify whether people have thought about decisions about credit
        and
        > to collect results into a report for coaches to view.
        >
        > Dean Oliver
        > Journal of Basketball Studies
        > www.rawbw.com/~deano/index.html
      • HoopStudies
        I won t say much yet on this, but I do want to introduce one aspect with regard to ... in ... off ... and ... One of the things I remember hearing about
        Message 3 of 10 , Mar 14, 2002
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          I won't say much yet on this, but I do want to introduce one aspect
          with regard to

          > > 9. A guard misses a jump shot, which is rebounded and stuck back
          in
          > > by a teammate. How much credit goes to the two players?
          > >
          >
          > Negative credit for the guard, unless you think he was passing it
          off
          > the rim. Two credits for the rebounder - 1) regaining possession,
          and
          > 2) making the basket.

          One of the things I remember hearing about Dominique Wilkins and have
          heard about Allen Iverson is that their shots are more often
          rebounded by their own team because their teammates know that they
          are going to shoot the ball. We already have put forth evidence (I
          think, I know I did the work) showing that Iverson's presence does
          help the Philly offense even though the boy sometimes can't hit the
          side of a barn with his shot.

          Just something to consider.

          DeanO
        • McKibbin, Stuart
          I m not looking for formal studies, but rather gut feel from people on these, maybe with some explanation for the answers, maybe without. 1. The point guard
          Message 4 of 10 , Mar 14, 2002
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            I'm not looking for formal studies, but rather gut feel from people
            on these, maybe with some explanation for the answers, maybe
            without.

            1. The point guard passes through the defense to a big man
            underneath the basket for a dunk. What percentage of the credit for
            the TEAM score should go to the passer vs. the scorer? Obviously,
            one player gets an assist and one gets the field goal, but,
            subjectively, should they split credit 50-50?

            If the pass is truly through the defense, that is, if the point guard had to see the opening and thread the ball at high velocity past defenders to the big man, (who then has to be able to handle the pass and not drop it) who dunks the ball without the defense being able to react then I'd give ALL of the credit to the PG. The PG made the play.

            2. A point guard passes to an unguarded mediocre shooter at the
            perimeter who makes a jump shot. How should credit be split here?

            NO credit should ever be given for making a basic pass. However, if the point guard penetrates and draws Mr. Mediocre's defender to him, and subsequently passes the ball to Mr. Mediocre who hits his wide open shot then PG should get ALL of the credit. Again, the PG made the play.


            9. A guard misses a jump shot, which is rebounded and stuck back in
            by a teammate. How much credit goes to the two players?

            I agree with others---what the hell did the guard do to earn credit? It sounds like his offensive rebounding teammate just bailed him out.

            10. A guard misses a jump shot, which is rebounded by a teammate.
            He passes back to the guard to restart the offense, which, after
            several passes, scores. How much credit should go to the offensive
            rebounder?

            No more than should be given a guy for grabbing a defensive rebound, or stealing the ball, or taking the ball out of the net. Or for that matter, to the opponent for kicking the ball out of bounds. In other words if the offensive rebound doesn't lead DIRECTLY to the basket, who cares how you got the ball?
          • dlirag
            ... back ... have ... A shot can be seen as a pass that results in one of the following things happening: 2 or 3 points are immediately scored (45% chance),
            Message 5 of 10 , Mar 29, 2002
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              --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
              > > > 9. A guard misses a jump shot, which is rebounded and stuck
              back
              > in
              > > > by a teammate. How much credit goes to the two players?
              > > >
              > >
              > > Negative credit for the guard, unless you think he was passing it
              > off
              > > the rim. Two credits for the rebounder - 1) regaining possession,
              > and
              > > 2) making the basket.
              >
              > One of the things I remember hearing about Dominique Wilkins and
              have
              > heard about Allen Iverson is that their shots are more often
              > rebounded by their own team because their teammates know that they
              > are going to shoot the ball. We already have put forth evidence (I
              > think, I know I did the work) showing that Iverson's presence does
              > help the Philly offense even though the boy sometimes can't hit the
              > side of a barn with his shot.

              A shot can be seen as a pass that results in one of the following
              things happening: 2 or 3 points are immediately scored (45% chance),
              the ball ends up in a teammate's hands (16% chance), or the ball goes
              to the opposing team (39% chance).

              Seen this way, a missed jump shot that's put back in by a teammate
              could be recast as a bad pass to a teammate who manages to score off
              this pass. Maybe one should allocate credit with this revised view of
              missed shots in mind, but I'm not yet sure.
            • HoopStudies
              ... they ... (I ... does ... the ... chance), ... goes ... This gets at what Gary Skoog did in one of James abstracts, where they assessed the expected runs
              Message 6 of 10 , Mar 29, 2002
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                --- In APBR_analysis@y..., "dlirag" <dlirag@h...> wrote:
                > >
                > > One of the things I remember hearing about Dominique Wilkins and
                > have
                > > heard about Allen Iverson is that their shots are more often
                > > rebounded by their own team because their teammates know that
                they
                > > are going to shoot the ball. We already have put forth evidence
                (I
                > > think, I know I did the work) showing that Iverson's presence
                does
                > > help the Philly offense even though the boy sometimes can't hit
                the
                > > side of a barn with his shot.
                >
                > A shot can be seen as a pass that results in one of the following
                > things happening: 2 or 3 points are immediately scored (45%
                chance),
                > the ball ends up in a teammate's hands (16% chance), or the ball
                goes
                > to the opposing team (39% chance).

                This gets at what Gary Skoog did in one of James' abstracts, where
                they assessed the expected runs for every given state and assigned
                credit/blame for transitions between those states.

                At the point before a shot, every possession is worth about 1 pt.
                After the shot, it could go to 2 pts with a made shot and end of
                possession, 3 pts with a made shot and end of possession, rare cases
                of >3 pts with or without continued possession, 0 pts with the
                probability of an offensive rebound (expected value of 1 pt after
                OR), 0 pts with probability of opponent getting the ball (expected
                value of 0 after DR). In the 0 pts with offensive rebound, you
                diminish the value of the missed shot by about 2/3 (assuming 1/3
                chance of OR), so, using relative to the mean credit (as Skoog did),
                the credit is -2/3 to the shooter who missed (bring expected points
                from 1 to 1/3), 2/3 to the offensive rebounder (who brought it back
                to 1), then 1 to the scorer (for going from 1 to 2). If this
                methodology is carried out in detail, you could modify the shooter-
                specific OR%, so that rather than diminishing Iverson's misses by
                2/3, you diminish them by 1/2 if you think that half of his misses
                are rebounded by the offense.

                Though in this case the rebounder and scorer are the same, note that
                there is more relative credit to the scorer (+1) than to the
                rebounder (+2/3). This may be in conflict with what the offensive
                rebound studies we did earlier here said, but I'd need to check.

                Dean Oliver
              • Michael K. Tamada
                ... [...] ... [...] This is how my model of basketball works. It can be used to generate means and standard deviations, but can even more directly be used to
                Message 7 of 10 , Mar 29, 2002
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                  On Fri, 29 Mar 2002, HoopStudies wrote:

                  > --- In APBR_analysis@y..., "dlirag" <dlirag@h...> wrote:

                  [...]

                  > > A shot can be seen as a pass that results in one of the following
                  > > things happening: 2 or 3 points are immediately scored (45%
                  > chance),
                  > > the ball ends up in a teammate's hands (16% chance), or the ball
                  > goes
                  > > to the opposing team (39% chance).
                  >
                  > This gets at what Gary Skoog did in one of James' abstracts, where
                  > they assessed the expected runs for every given state and assigned
                  > credit/blame for transitions between those states.
                  >
                  > At the point before a shot, every possession is worth about 1 pt.
                  > After the shot, it could go to 2 pts with a made shot and end of
                  > possession, 3 pts with a made shot and end of possession, rare cases

                  [...]

                  This is how my model of basketball works. It can be used to generate
                  means and standard deviations, but can even more directly be used to
                  estimate win probabilities. The trouble is that the models make it easy
                  and tempting to assign all the credit for an action to a player, e.g. the
                  offensive rebounder gets the +2/3 that you describe, when some of the
                  credit perhaps should go to teammates who blocked out (unlikely however in
                  an offensive rebounding situation) and maybe some of the blame should go
                  to the defensive rebounder who failed to block the guy out. So this model
                  makes assignment of credit to players easy to do -- but not necessarily
                  truly accurate.

                  > Though in this case the rebounder and scorer are the same, note that
                  > there is more relative credit to the scorer (+1) than to the
                  > rebounder (+2/3). This may be in conflict with what the offensive
                  > rebound studies we did earlier here said, but I'd need to check.

                  No, scoring a field goal is clearly more valuable than grabbing an
                  offensive rebound, even when the loss of possession is taken into account.
                  Missing a field goal is the act that is approximately equal to an
                  offensive rebound.


                  --MKT
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